Separation dynamics of ullage rockets

Abstract

The dynamics associated with the jettisoning of spent ullage rocket systems from the parent launch vehicle is investigated. The analysis considers a spring-based mechanism employed to jettison the system hinged on to an accelerating stage. Closed-form solutions are obtained. Analytical expressions are developed for the hinge reactions. Conditions are derived for optimum separation velocity and guidelines presented for selection of design parameters. The influence of residual thrust of ullage rockets on the separation process is examined and the expressions for its permissible value developed. a b E h /n/. Nomenclature = constant longitudinal acceleration of the thrusting stage = distance of the nozzle throat from the hinge (Fig. 1) = net stored spring energy -longitudinal distance between the spring and the hinge (Fig. 1) =X 3 -mass moment of inertia of the spent ullage system about the hinge, and its own mass center, respectively k = effective stiffness of the springs e = distance of the mass center from the hinge (Fig. 1) M = moment about the hinge due to the residual thrust m = mass of the spent ullage system M cl , M c2 , M c3 = critical values of the moments about the hinge, Eqs. (26), (30), and (34) M cl ,M c2 , M c3 = normalized critical values of the moments, M ci = lateral and longitudinal hinge reactions (Fig. 1) Rajeev Lochan graduated with a degree in mechanical engineering from BIT Sindri (Bihar), India, in 1973 and received his Master's in aeronautical engineering from the Indian Institute of Technology (IIT) Kanpur in 1976.He participated in the development of a trisonic wind tunnel at IIT Kanpur before joining Vikram Sarabhai Space Center (VSSC) Trivandrum, in 1977. Since then, he has been engaged in the research of diverse aspects of flight mechanics of launch vehicles. Dynamics of separating bodies, deployment dynamics, boost phase guidance, and onboard algorithms for position and attitude determination are some of the areas where he has made contributions.

Analysis of two-stage endo-atmospheric separation using statistical methods

“…As mentioned before, the statistical analysis will be performed using two approaches. The Monte Carlo technique suggested by many researchers such as Lochan et al (1994), Choi et al (2002) and Jeyakumar and Rao (2006) is ideal, specially for nonlinear systems. It is numerically based on the provision of random data and numerous execution of the simulation code that is achieved by basically adding an extra outer loop around the SepPak.…”

“…To create a safe distance in minimum time, attitude motors could also be used. Since the separation process is not deterministic and there are uncertainties in the system parameter selection, it would be useful to utilize random variables in the dynamic modeling of the separation process (Lochan et al, 1994). Figure 1a shows the parachute and the payload as well as the forces acting on them.…”

Rigid body separation dynamics for space launch vehicles

“…Seongjin Choi et al (15) developed an efficient three-dimensional aerodynamic-dynamic coupled code to simulate the separation dynamics of strap-on boosters in the dense atmosphere. Lochan et al (16)(17)(18)(19) analysed the separation dynamics of strap-on boosters from the core rocket utilising the wind tunnel simulation data for dynamic forces and ullage rockets. Jeyakumar and Biswas (20)(21)(22)(23)(24) provided stage separation system design and dynamic analysis of ISRO launch vehicles.…”

Dynamics of nose cone jettisoning from spinning rockets

“…Levi Civita density function  coning angle [equation (11)] ! frequency parameter representing coning motion [equation (10)] à ratio of transverse moment of inertia to that of the longitudinal for a dynamically symmetric body I T /I L "…”